Technology OV – Structure of TS, DVB Service and ES in DVB-H

Structure of TS, DVB Service and ES in DVB-H

1). Structure – TS, DVB Service and ES:

§ Figure - represents the global hierarchical structure of DVB broadcast networks, as used by DVB-T and DVB-H.

§ DVB Network à comprises several Multiplex(es) in Transport Streams à comprises several DVB service(s) à comprises a set of Elementary Streams

http://docs.google.com/View?id=ddh56dhg_199dmbg5pf5

§ The overall principle is based on MPEG-2 transport streams, as defined in the corresponding MPEG-2 standard.

§ A set of ESs that constitutes a semantic entity when grouped and synchronized together is called a DVB service (also a program, from the vocabulary used in the MPEG-2 standard). An example is one DVB service carrying a TV channel that comprises one ES for its video content, one ES for its audio content, and one ES for each language in which subtitles are available.

§ For transmission purposes, several DVB services are multiplexed together in the form of a single signal (a terrestrial radio signal in the case of DVB-T/DVB-H). This is performed to obtain an MPEG-2 transport stream (TS) as defined by the MPEG-2 standard.

§ Datagrams shall be encapsulated using Multi-Protocol Encapsulation (MPE).

§ Time-slicing shall be used on elementary streams carrying MPE sections.

§ MPE-FEC should be used on elementary streams using time-slicing.

2). ES - Packetized Elementary Stream (PES) Data:

§ ES data is first divided in packetized elementary stream (PES) packets

http://docs.google.com/View?id=ddh56dhg_201frq6dvfv

3). TS – Transport Stream Packet:

§ The PES packets are then broken down into fixed-size transport packets (TS packets). Doing so provides a way to combine several ESs into one single TS.

§ The structure of TS packets is shown below:

http://docs.google.com/View?id=ddh56dhg_203f4przgds

§ The size of the TS packets is fixed at 188 bytes each (or 204 if 16 bytes of optional error correction code is added).

§ Each packet starts with a header of 4 bytes. For the most common packets, that is, those without an adaptation field, the header is followed by 184 bytes of payload.

§ The most important fields of the header are the synchronization byte and the packet identifier (PID).

§ The synchronization byte allows the receiver to identify the start of a TS packet.

§ The PID associates the TS packet with one of the elementary streams carried by the transport stream.